High-speed stylographic apparatus and system



I Julie 24, 1969 w s0 3,452,360

HIGH-SPEED STYLOGRAPHIC APPARATUS AND SYSTEM FiledJuly. 28. 1967 Sheetof 2 l l T is [ll/l1 f IN VEN TOR.

ROBERT R. WILLIAMSON BY (7 ATTORNEY June 24, 1969 R. R. WILLIAMSON 3,

I HIGHSPEED STYLOGRAPHIC APPARATUS AND SYSTEM Filed July 28, 1967 Sheet2 of 2 MODULATOR I- COMPUTER 4'---|NPUT AMPLI Fl ER OSCILLATOR FIG.6

INVENTOR.

ROBERT R. WILLIAMSON ATTORNEY United States Patent O 3,452,360HIGH-SPEED STYLOGRAPHIC APPARATUS AND SYSTEM Robert R. Williamson,Glendale, Calif., assignor to General Precision Systems Inc., acorporation of Delaware Filed July 28, 1967, Ser. No. 656,817 Int. Cl.G01d 15/18 U.S. Cl. 346140 7 Claims I ABSTRACT OF THE DISCLOSURE Anink-ejecting stylograph and a system for its use in high-speed printingand writing. A pen barrel, Supplied with ink fluid and having a flexiblenozzle at one end, is provided with a magnetostrictive rod immersed inthe ink and extending inside the barrel to the region of the nozzle. Themagnetostrictive rod is excited by a highfrequency driving signal,modified in accordance with an information signal which causes the rodto flex said nozzle and to eject minute droplets of ink, in quantity,size and timing in accordance with the information signal. The ejectedink droplets are received upon a web of paper or other recording surfacemoving at a known speed, in close proximity to the nozzle.

BACKGROUND OF THE INVENTION This invention relates to the art ofprinting or writing. More particularly, it relates to an ink-ejectingstylograph or pen for writing or printing upon a receiving surface inresponse to information signals, and to a system for its employment.

High-speed printers are known in which ink under pressure is ejected inthe form of droplets, from a rapidly vibrating nozzle. The droplets areelectrically charged and pass through a deflecting field created betweencharged plates, the field being varied in accordance with an informationsignal in order to deposit the droplets at desired locations upon amoving web of paper, and thus to form intelligible writing or printing.Such an arrangement is shown in the patent to R. A. Adams et al., No.3,281,860, issued Oct. 25, 1966. In such prior art systems, the dropletsare of uniform size and, in passing through the deflecting field, travela considerable distance to the writing medium. During a comparativelylong transit time, they must be charged as they leave the nozzle, mustform into droplets of uniform size, and must then be deflected to anexact point of impact on the moving web of paper, providing manypossibilities for error, in a process which should be substantiallyerror free, and, moreover, slowing the process.

SUMMARY Difliculties with ink-ejecting printers in the prior art havebeen obviated by the high-speed stylographic system and apparatus of theapplicant. According to the invention, a magnetostrictive rod, immersedin an inkcontaining barrel having a flexible nozzle, expands andcontracts in accordance with high-frequency electromagnetic excitation,flexing said nozzle and ejecting minute droplets from a nozzle operatingin close proximity to a moving web of paper or other writing medium. Theexcitation signal supplied to the stylograph is modulated in accordancewith information supplied from a computer system, so that the dropletsof ink ejected from the stylograph nozzle at any instant are of a sizeand number to imprint a desired incremental portion of an alphanumericcharacter, half-tone reproduction, or whatever.

It is therefore an object of the invention to provide a "ice high-speedstylograph or ink ejector which will operate in close proximity to arapidly moving Web of writing medium. It is a further object of theinvention to provide a high-speed stylograph in which minute inkdroplets ejected from the nozzle can be varied in size and number asdesired at a given instant. It is yet another object of the invention toprovide a high-speed stylographic system in which multiple stylographscan be arranged in battery and linked with a computer, so that even avery wide web of paper or other writing medium, such as newsprint,moving at high speed, can be adequately covered, and the detail renderedwill be sufficiently fine for use in a half-tone reproduction process,for example.

These and other objects of the invention will be apparent from theensuing description and from the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is an elevational view of astylograph according to the invention;

FIGURE 2 is a longitudinal cross section of the stylograph of FIGURE 1,taken along the line 2-2, but showing the magnetostriction rod inelevation;

FIGURE 3 is an enlarged cross section taken along the line 33 of FIGURE2;

FIGURE 4 is an enlarged cross-sectional view of the nozzle, taken alongthe line 4-4 of FIGURE 2;

FIGURE 5 shows schematically the manner in which multiple stylographsmay be employed to provide coverage across the width of a moving web ofwriting medium; and

FIGURE 6 is a block diagram of the circuitry employed in a stylographicsystem according to the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGURES l-4 of thedrawings, there is shown a stylograph 10, having a generallycylindrical, tubular barrel 12, providing at one end with a nozzle 14which blends from a generally circular cross section where it joins thebarrel 12 to a generally elliptical cross section (FIGURE 4), near itsmidpoint and to its terminus, where it is provided with a very small,preferably elliptical, delivery orifice 16. The barrel 12 is suppliedwith fluid ink through a supply connection 18, connected by a conduit 20to a source of ink (not shown). The barrel, nozzle, and supplyconnection may be of unitary construction, molded in one piece from asuitable structural plastic such as a polyamide or acetal resin. Thewall of the nozzle 14 is made thinner, and therefore more flexible, thanthe wall of the barrel 12, for a reason presently to be explained.

The end 22 of barrel 12, opposite the nozzle 14, is closed by means of asealing plug or sleeve 24, preferably made of an elastomeric dampingmaterial such as one of the silicone rubber sealant compounds suppliedby General Electric, Dow-Corning, and other manufacturers.

A magnetostriction rod or plunger 26 extends into the barrel 12 and hasits forward end 28 terminated adjacent the nozzle 14, its after end 30projecting from the end 22 of the barrel 12 and being sealed by the plug24. An electrical excitation coil 32 is wound upon a plastic insulatingsleeve 34, fitted upon the after end 30 of the rod 26. Electrical leads36 extend from the excitation coil 32 and are connected to the source ofa driving signal.

A typical stylograph according to the invention has a magnetostrictionrod or plunger of about 0.01 inch in diameter and from 3 to 6 inches inlength, with a barrel length of about 2 to 4 inches, a barrel externaldiameter of, typically, about 0.20 inch, and a barrel wall 0.010 inchthick. The major diameter of the elliptical orifice 3 16 is of the orderof 0.013 inch, or about the size of a No. 80 drill. The -wall of thenozzle 14 tapers in thickness from 0.010 inch where it joins the barrel12, to about 0.003 inch at the delivery orifice 16.

The excitation coil 32 of the stylograph, typically, is made with aboutto 20 turns of No. 30, Formvar insulated, copper magnet wire, Wound upona sleeve 34 of suitable plastic tubing, snuggly fitted to the after end30 of the magnetostriction rod 26. The sleeve is, however, slidable uponthe rod, so that the coil can be shifted'in position in the process ofadjusting and tuning the stylograph for maximum efiectiveness.

As mentioned previously, the stylograph of the invention is intended tobe operated in close proximity to the Writing medium. A typicaloperating distance, from the end of the nozzle 14 at the deliveryorifice 16, to the web 40, is 0.001 to 0.005 inch. The nozzle need onlybe placed far enough from the web so that the minute droplets issuingcan form as discrete entities without smearmg.

In the operation of the stylograph according to the invention, a drivingsignal, AM, or otherwise modulated in accordance with an output from acomputer or other source, as indicated in FIGURE 6, is impressed, atpreferably 500 to 2000 kilohertz carrier frequency, upon the excitationwinding 32. In response to this excitation, the magnetostriction rod 26expands and contracts at this frequency, and with each expansion,displaces a minute amount of ink. In the build up of pressure occasionedby each minute expansion of the magnetostriction rod 26, there is abuild up in fluid pressure within the stylograph barrel 12, entailing aminute flexing of the wall of the nozzle 14, which, as previouslymentioned, is generally elliptical and thinner than the main portion ofthe barrel.

When the fluid pressure in the barrel builds up with each expansionstroke of the rod 26, the elliptical wall of the nozzle 14 and orifice16 flexes and tends to assume a more circular shape and a largerperiphery, otfering less resistance to flow through it. Upon the ensuingfull contraction of the rod 26 and its consequently decreaseddisplacement, the fluid pressure drops to a slightly negative value,i.e., a lesser value than when the rod is at its neutral dimension, andthe wall of the nozzle and orifice tends to return beyond its normalelliptical shape, to a smaller-thanf-normal periphery, having a slightlyincreased resistance to flow. This slightly increased flow resistance ofthe nozzle, upon contraction of the rod, slightly impedes back flow ofink. The aggregate result is a slight check valve or diode action,resulting in the ejection of a minute droplet of ink from the orifice16, because of fluid displacement by the rod 26.

An additional factor contributing to the diode or check valve effectarises out of the irreversibility of droplet formation under surfacetension. Once having been ejected and formed, or nearly so, a dropletwill tend not to coalesce back into the cohesive body of fluid fromwhich it came.

Referring to FIGURE 5, a battery 38 of the stylographs 10, is showndisposed across the width of and in close proximity to a web 40, ofpaper or other writing medium moving in the direction indicated by thearrow. For purposes of illustration, a single row of stylographs isshown, placed as closely together as their barrel diameters will permit.However, for printing of the fineness of a typical newspaper half-tonescreen, for example, multiple rows of stylographs stepped echelon areemployed, each row slightly offset from the preceding row, so that thepaths traced by the stylographs on the moving web 40 are spaced apart adistance equal to the center-to-center distance of two adjoininghalf-tone dots.

In FIGURE 6, a block diagram is shown of the circuitry employed in theoperation of a multiple stylograph system according to the invention.The excitation coil 32 about the magnetostriction rod 26 is connected toan amplifier 42, which supplies the driving signal to the coil in orderto excite the rod. The amplifier is supplied with power from anoscillator 44 at a carrier frequency preferably in the range of from 500to 2000 kilohertz, for example. The carrier signal is modulated by anoutput from a modulator 46, in accordance with a command signal receivedfrom a computer 48. Into the computer are supplied the necessaryinformation signals representative of the speed of the web 40 and thesize and location of the droplets of ink to be ejected by a particularstylograph at a specific instant, in order to print, by incrementalbuild up, the desired graphic output on the web 40.

The source of information to the computer 48 may be, for example, anysuitable known mechanism for scanning graphic or other displays,photographic negatives, positives or transparencies, in order to supplya reprcsentative input to the computer and instruct the system to printthe desired reproduction. Many other uses of the invention will suggestthemselves to those skilled in the art.

It will be understood by those skilled in the art that the embodiments,dimensions, materials, and other design criteria given herein are merelyexemplary, and are not to be regarded as limitative of the breadth andscope of the invention.

I claim:

1. stylograph for high-speed writing and printing, comprising:

an ink container having flexible ink delivery nozzle connected thereto;an ink delivery orifice at the terminus of said nozzle; amagnetostriction rod disposed for immersion in the contents of saidcontainer, one end of said rod terminating in proximity to said nozzle,said nozzle being responsive to the operation of said rod; and

means for magnetically exciting said rod so that the stroke of said rodflexes said nozzle to eject droplets of ink therefrom.

2. stylograph for high-speed writing and printing, comprrsmg:

an ink barrel of generally tubular form, one end of said barrel beingopen and the other end having a pointed nozzle, the walls of said barreland nozzle being constructed of a resilient material, the wall of thenozzle being generally thinner than the wall of the barrel;

an ink delivery orifice at the terminus of said nozzle;

a magnetostriction rod within said barrel, one end of said rodterminating in proximity to said nozzle, said nozzle being responsive tothe operation of said rod, and the other end projecting from the openend of said barrel;

means for magnetically exciting said rod so that the stroke of said rodminutely flexes said nozzle to eject droplets of ink therefrom; and

fluid-tight means for sealing the entry of said rod into the end of saidbarrel.

3. A stylograph according to claim 2, in which the wall of the nozzle isthinner toward its delivery end than at its end adjoining the barrel.

4. A stylograph according to claim 2, in which the nozzle blends incross section from the shape of the barrel where joined thereto, to agenerally elliptical cross section toward the delivery orifice.

5. A stylograph according to claim 2, in which the magnetostriction rodis encircled by an electrical excitation coil.

6. A stylograph according to claim 2, in which the sealing means isconstructed of a vibration absorbing material.

7. In a high-speed stylographic printing system, the combination of: Y

a battery of electromagnetically excited, magnetostriction actuatedstylographs, each disposed upon receipt of an excitation signal, todeliver ink upon a web of References Cited writing material moving at aknown speed, each also having a flexible nozzle responsive to expand andUNITED STATES PATENTS contract when said stylographs are electromag- 2512,743 6/1950 Han en.

3:??? g ff Odul ted e .tatio ignal to 5 2,951,894 9/1960 Hirsch 346-440X mm o ppyigam a XCl ns each of Said stylographs; 3,334,354 8/1967Mutschler 346-140 means modulatmg Said. F Q slgnal accord RICHARD B.WILKINSON, Primary Examiner.

ance with a command signal Indicative of the speed of said web and adesired graphic print-out; and JOSEPH W. HARTARY, Assistant Examiner.means for supplying said command signal to said modulating means.

